【作者】 王飞；

【导师】 王梦恕； 袁大军；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2014， 博士

【摘要】 摘要：盾构掘进遭遇障碍物桩基时,直接切桩相比于传统方法,影响周边环境小、成本低、工期短,社会及经济效益显著,但目前切桩理论研究与实施技术在国际范围内尚远未成熟,尤其是对于切削大直径桩基。本文依托苏州地铁盾构切削14根中1000～1200mm桥梁桩基工程,综合采用调研、理论分析、有限元仿真、现场试验和工程实测等研究手段,对盾构直接掘削大直径钢筋混凝土群桩的相关机理、理论与技术进行研究。主要研究内容和成果如下：(1)综合考虑材料非线性、几何非线性以及接触非线性,以国际大型非线性显式动力软件为分析平台,对刀刃切削钢筋、混凝土的切削过程、相互作用及细观切削机理进行了研究。(2)切削钢筋混凝土桩基应选用负前角、双面刃的刀具；通过有限元仿真获得了刀刃前角、刃角、刃宽等对切筋、切砼的影响规律,并以适应连续切削大直径桩基为目标,研发出了新型切桩专用刀具；通过建立三维切削钢筋热力耦合模型和三维切削混凝土全过程模型,揭示了新型刀具的动态切削过程及切削性能；结合仿真计算结果并对比各种磨损类型的发生条件,指出刀具合金切削钢筋、混凝土对应的磨损机理为硬质点磨粒磨损。(3)从理论上对切桩刀盘刀具配置进行了深入研究：刀具布置形式可采用同心圆法,相邻刀具宜以等相位角差值进行定位,切削轨迹的间距确定应以能实现全覆盖面切削混凝土为原则；考虑掘削桩基对刀盘刀具的多功能需求,提出了包括有正面大贝壳刀、边缘大贝壳刀、中心小贝壳刀、仿形贝壳刀以及羊角储备刀在内的刀盘群刀综合配置方案。(4)通过建立刀盘切桩数学模型,编制刀盘受力计算程序,获得了推力扭矩与刀盘不平衡力的变化特征,以及桩基尺寸大小、偏移距离对刀盘受力的影响规律,并给出了相应的主动掘削参数设置建议；采用国际大型机械设计软件建立了切桩刀盘刀具模型,并针对最不利的切削工况,对刀盘刚度进行检算并提出了加固措施。(5)开展了国内外首次的盾构直接切削钢筋混凝土桩基现场试验,分析了切桩效果、刀具损伤规律以及掘削参数特征等,对刀具配置和掘削参数初步方案的合理性进行了验证,并根据试验结果提出了超前贝壳刀的优化配置方案及分次切筋的切削理念,其切削效果得到了群刀切削仿真实验的证实,并最终在工程实践中得到成功应用。(6)以苏州地铁盾构切削14根大直径桥梁群桩工程为依托,探讨了切桩条件下的上部结构与管片衬砌的安全性能；从刀盘刀具、螺旋输送机、小流量推进泵、外包管等多方面研究提出了盾构综合改造加强方案；形成了以“慢推速、中转速、保土压、注惰浆、控姿态”为核心的盾构掘削大直径桩基施工控制技术。更多还原

【Abstract】 ABSTRACT:While encountering pile obstacles during shield tunneling, the method of cutting pile directly has the advantage of small impact on surrounding environment, low cost and short construction period compared to traditional methods, as a result, its social and economic benefit is remarkable. However, the theory research and implementation technology of cutting piles are far from mature in the international scope currently, especially for cutting large-diameter reinforced concrete piles. Based on the construction of shield cutting14Φ1000～1200mm diameter bridge piles in Suzhou subway, the related mechanism, theory and technology of shield cutting reinforced concrete piles are studied by using investigation, theoretical analysis, finite element simulation, field test as well as construction measuring. The major contents and achievements of the study are as follows:(1) Considering material nonlinearity, geometric nonlinearity and contact nonlinearity, the whole process, interaction and mesoscopic mechanism of blade cutting steel, concrete were studied with the analysis platform of international famous nonlinear explicit dynamic software.(2) The shell cutter of negative front angle with double-side blade is fit for cutting piles. The influence laws of front angle, blade angle and blade width on cutting steel, concrete were obtained through finite element simulation. In order to adapt the continuous cutting of large-diameter reinforced concrete piles, a new type of cutting pile tool was invented. By establishing three-dimensional thermodynamic coupling model of cutting steel and three-dimensional whole-process model of cutting concrete, the dynamic cutting process and cutting performance of the new cutting tool were revealed. According to the simulation results, the wear mechanism of tool alloy when cutting steel, concrete was considered as hard point abrasive wear by comparing various wear types.(3) The cutting tools configuration was studied theoretically:Cutter layout can adopt the method of concentric circles, adjacent cutters should be positioned with equal phase angle, the determination of cutter spacing should cover the entire cutting plane of pile concrete. An integrated configuration scheme including obverse shell tools, edge shell tools, center small shell tools, overbeaking shell tools as well as claw tools was proposed in order to meet the multi-function requirements of cutting piles. (4) The mathematical model of cutterheand cutting pile was set up and the corresponding force calculation program was created, then the change characteristics and influence laws of thrust, torque and unbalanced force were obtained. The active cutting parameter setting suggestions were given for cutting piles of different size and offset distance. With the help of international mechanical design software, the cutterhead and tools models were drew, then the cutterhead stiffness was checked and reinforcement measures were put forward for the most unfavorable cutting conditions.(5)The field test of shield cutting reinforced concrete pile directly was carried out for the first time both at home and abroad, the cutting effect, tool damage law and cutting parameters characteristics were analyzed, meanwhile, the rationality of preliminary scheme of the tool configuration and cutting parameters settings was checked. The layout scheme of advancing shell tool and the concept of cutting rebar with different times were presented according to the experiment results, which was then confirmed by simulation, and was successfully applied in engineering practice eventually.(6) Taking Suzhou subway shield cutting large-diameter bridge piles as project background, the security performances of upper structure and segment lining under the condition of cutting piles were discussed, a comprehensive shield strengthening scheme was put forward, including cutter tools, screw conveyor, small flow pump and outside pipes. Slow advancing speed, medium rotation speed, stabile soil pressure, inert slurry and strict shield attitude were suggested to control the construction of cutting large-diameter piles.更多还原